Support json or file path for GCP Account Key.
Support json or file path for GCP Account Key.

[#145648427]

Signed-off-by: Dan Rabinovitch <2e9e16325b2f8d8c0df5801edb6f11a5696b43e2@gmail.com>

pivotal-cf-experimental/bosh-bootloader,niroyb/bosh-bootloader,pivotal-cf-experimental/bosh-bootloader,niroyb/bosh-bootloader